Prior research indicates that early pubertal timing is associated with aggressive behavior, particularly in the context of adversity as postulated in the contextual amplification hypothesis. However, few studies have examined harsh parenting as the context for the effect of early pubertal timing. Even fewer studies have tested the interactive effect of early pubertal timing and positive parenting on aggressive behavior. In this study, we tested the proposition that early pubertal timing, contrary to the general conception of it as a vulnerability, indexed susceptibility, and thus early maturing individuals were affected more by their environment in a “for better and for worse” manner. The sample consisted of 411 community‐recruited youth aged 11–12 years (51% boys, 80% African Americans). Participants reported Tanner Stages of pubertal development, aggressive behavior and harsh parenting practice of their parents. Puberty scores were standardized with groups of the same age, sex, and ethnicity, and those that scored the top one‐third were defined as early maturing individuals. Parents reported youth's aggressive behavior and their parenting practices towards the youth, including harsh parenting and positive parenting. Early pubertal timing significantly moderated the relationship between harsh/positive parenting and aggressive behavior. Specifically, harsh parenting was positively associated with aggressive behavior to a larger degree among early maturing individuals than among on‐time/late‐maturing individuals. Positive parenting was inversely associated with aggressive behavior but only among early maturing individuals. This study is the first to document support for early pubertal timing as susceptibility to the environmental influences in relation to aggressive behavior. Theoretical and intervention implications are discussed.